Triazole vs. triazolium carbene ligands in the site-selective cyclometallation of o-carboranes by M(iii) (M = Ir, Rh) complexes

2018 ◽  
Vol 47 (30) ◽  
pp. 9975-9979 ◽  
Author(s):  
María Frutos ◽  
Mar Gómez-Gallego ◽  
Elena A. Giner ◽  
Miguel A. Sierra ◽  
Carmen Ramírez de Arellano
Keyword(s):  
Bond Activation ◽  
Carbene Ligands ◽  
Triazole Ligand ◽  
Site Selective

M(iii)-mediated (M = Ir, Rh) site-selective cage B–H and C–H bond activation in o-carboranylmethyl derivatives has been achieved by switching the electron donating properties of the 1,2,3-triazole ligand.

Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

2017 ◽  
Author(s):  
Haibo Ge ◽  
Lei Pan ◽  
Piaoping Tang ◽  
Ke Yang ◽  
Mian Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Bond Functionalization ◽  
Aliphatic Ketones ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp<sup>3</sup> carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp<sup>3</sup>)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp<sup>3</sup>)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br><br>

ChemInform Abstract: Non-Coordinating-Anion-Directed Reversal of Activation Site: Selective C-H Bond Activation of N-Aryl Rings.

ChemInform ◽  
2016 ◽  
Vol 47 (45) ◽  
Author(s):  
Dawei Wang ◽  
Xiaoli Yu ◽  
Xiang Xu ◽  
Bingyang Ge ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Site Selective ◽  
Activation Site

Carbon Dioxide-Driven Palladium-Catalyzed C–H Activation of Amines: A Unified Approach for the Arylation of Aliphatic and Aromatic Primary and Secondary Amines

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 519-524 ◽  
Author(s):  
Michael Young ◽  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Justin Maxwell ◽  
Daniel Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bond Activation ◽  
Secondary Amines ◽  
Activation Process ◽  
Unified Approach ◽  
Benzylic Amines ◽  
Palladium Catalyzed ◽  
Group A ◽  
Directing Group ◽  
Site Selective

Amines are an important class of compounds in organic chemistry and serve as an important motif in various industries, including pharmaceuticals, agrochemicals, and biotechnology. Several methods have been developed for the C–H functionalization of amines using various directing groups, but functionalization of free amines remains a challenge. Here, we discuss our recently developed carbon dioxide driven highly site-selective γ-arylation of alkyl- and benzylic amines via a palladium-catalyzed C–H bond-activation process. By using carbon dioxide as an inexpensive, sustainable, and transient directing group, a wide variety of amines were arylated at either γ-sp3 or sp2 carbon–hydrogen bonds with high selectivity based on substrate and conditions. This newly developed strategy provides straightforward access to important scaffolds in organic and medicinal chemistry without the need for any expensive directing groups.1 Introduction2 C(sp3)–H Arylation of Aliphatic Amines3 C(sp2)–H Arylation of Benzylamines4 Mechanistic Questions5 Future Outlook

Computational Studies of Intramolecular Carbon−Heteroatom Bond Activation of N-Aryl Heterocyclic Carbene Ligands

2008 ◽  
Vol 27 (5) ◽  
pp. 938-944 ◽  
Author(s):  
Richard A. Diggle ◽  
Andrew A. Kennedy ◽  
Stuart A. Macgregor ◽  
Michael K. Whittlesey
Keyword(s):  
Bond Activation ◽  
Computational Studies ◽  
Carbene Ligands

scholarly journals Smooth C(alkyl)–H bond activation in rhodium complexes comprising abnormal carbene ligands

2011 ◽  
Vol 40 (38) ◽  
pp. 9911 ◽  
Author(s):  
Anneke Krüger ◽  
L. Jonas L. Häller ◽  
Helge Müller-Bunz ◽  
Olha Serada ◽  
Antonia Neels ◽  
...  
Keyword(s):  
Bond Activation ◽  
Rhodium Complexes ◽  
Carbene Ligands

Transition-metal-free site-selective C–F bond activation for synthesis of 8-aminoquinolines

2017 ◽  
Vol 58 (45) ◽  
pp. 4240-4242 ◽  
Author(s):  
Jianping Chen ◽  
Dongyang Huang ◽  
Yuqiang Ding
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Metal Free ◽  
Site Selective

scholarly journals Abnormal N-heterocyclic Carbenes: More than Just Exceptionally Strong Donor Ligands

2011 ◽  
Vol 64 (8) ◽  
pp. 1113 ◽  
Author(s):  
Anneke Krüger ◽  
Martin Albrecht
Keyword(s):  
Water Oxidation ◽  
Bond Activation ◽  
Heterocyclic Carbenes ◽  
Oxidation Catalysis ◽  
Donor Ligands ◽  
Free Alcohol ◽  
Carbene Ligands ◽  
Transfer Processes ◽  
Oxidative Transformations ◽  
Electron Transfer Processes

Complexes comprising a so-called abnormal carbene ligand, which displays pronounced mesoionic character, have recently been shown to be competent catalyst precursors for bond activation processes and oxidative transformations, including base-free alcohol oxidation and water oxidation. In this highlight we propose that these abnormal carbene ligands are not just useful spectator ligands but also actively participate in the bond activation step. This mode of action is partially based on the exceptionally strong donor properties of the ligand and, specifically, on the mesoionic character of these abnormal carbenes. The mesoionic properties provide a reservoir for charges and holes and thus induce efficient ligand-metal cooperativity, which is beneficial in particular for oxidation catalysis that involves concerted proton and electron transfer processes.

Phosphine-catalyzed remote α-C–H bond activation of alcohols or amines triggered by the radical trifluoromethylation of alkenes: reaction development and mechanistic insights

2017 ◽  
Vol 4 (11) ◽  
pp. 2139-2146 ◽  
Author(s):  
Lei Li ◽  
Liu Ye ◽  
Shao-Fei Ni ◽  
Zhong-Liang Li ◽  
Su Chen ◽  
...  
Keyword(s):  
Bond Activation ◽  
Activation Of Alcohols ◽  
Site Selective

An efficient radical protocol for concomitant functionalization of both alkenes and remote α-C–H bonds of alcohols or amines via 1,5(6,7)-HAT was realized in a highly controlled site-selective manner.

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